The present invention relates styluses for detecting signals stored in the form of geometric variations in a recording medium as capacitance variations, and in particular to a stylus including a diamond body having the same wear resistance property as the wear resistance property of the stylus electrode attached thereto.
Conventional styluses for use in detecting signals as electrostatic capacitance variations recorded as geometric variations in a recording medium such as grooveless disc have an electrode bonded to one surface of an insulative supporting body formed of diamond or sapphire. The stylus of this type rests over several spiral tracks in which the signals are recorded. The electrode is machined so that its width substantially corresponds to the width of the track to read one information signal and the tracking signals on either side of it to keep the stylus on the right path as the disc spins at a high speed.
However, it was found that the stylus electrode has the tendency toward wearing at a higher rate than the rate at which the diamond body wears on its contact face and as a result the downward tip of the electrode is spaced above the contact face of the diamond body after a period of use, thus degrading the operating performance of the stylus and imposing limitations on the useful lifetime of the stylus.